| Probiotic lactic acid bacteria (LAB) have a variety of physiological functions, and the antioxidant activity and lipid-lowering functions have drawn more and more attention currently. In this study, we adopted 52 strains isolated from fresh tomatoes, raw milk and fermented Chinese cabbage. All strains were analyzed by randomly amplified polymorphic DNA (RAPD) and hierarchical cluster. Among of them, 2 strains of N2 and X9 with the better antioxidant activity were selected out by antioxidant test in vitro and identificated by 16S rDNA and biochemical tests. In order to confirm effects of antioxidation and hypolipidemic in vivo, N2 and X9 were used to feed kunming mice.The antioxidant experiments in vitro showed that 32 strains exhibited antioxidant activity. The extends of the activities of scavenging superoxide anion radicals and hydroxyl radicals were ranging from 3.19% to 25.24% and 11.00% to 83.58%, respectively. Meanwhile, the inhibition activity range of anti-lipid peroxidation was 0.39~57.86%. N2 and X9 which selected out were identificated as L.casei and L.plantarum.The animal experiments showed that the strains could increase the levels of SOD and GSH-px, and decrease the content of MDA, but the changes in CAT were insignificant in different groups. Meanwhile, the two strains could decrease TC, TG and LDL-c in various degrees on hyperlipidemic mice. The effects of X9 groups were higher than that of N2 groups.The further research indicated that the number of peripheral blood CD4+ T cell in each group was increased compared to its corresponding control group, which suggested that the two strains could enhance the immunity of the mice. The Nrf2 protein expression was also investigated in liver and the result showed that the two strains may activate the Nrf2 to against oxidative damages.
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